Automobiles have long employed pumps for delivering fuel from a fuel tank to an internal combustion engine. For example, early automotive applications used mechanically actuated diaphragm type pumps mounted directly to the engine; these pumps "pulled" fuel from the fuel tank to the pump and then "pushed" it to the carburetor for mixture with air prior to being delivered to the engine's cylinders for combustion. Current fuel pumps are usually mounted within the fuel tank, and deliver fuel to the fuel injector(s) at high pressures (40 psi) through various rotary means, such as an impeller or gerotor. These pumps, however, often cavitate thus producing undesirable fuel vapor bubbles within the fuel which reduces engine performance and decreases efficiency.
An additional problem with present fuel delivery systems is fuel vaporization. Fuel stored within the fuel tank evaporates and the vapor collects above the fuel in the tank. Normal diurnal temperature changes and returned, unused hot fuel (in recirculating fuel delivery systems) accelerate this fuel vaporization. As a result of governmental regulation of emissions of this fuel vapor, automobile manufacturers have devised numerous methods and apparatus for the storage and handling of fuel vapor which would otherwise escape to the atmosphere, both during operation and upon refueling, or during vehicle operation. Such apparatus adds to vehicle expense by increasing research, engineering, design, manufacturing and assembly costs.